Introduction to Fungi, Third Edition

AQUATIC HYPHOMYCETES (INGOLDIAN FUNGI)
685
the fundamental problem of their low saprotrophic
capacity. The latter feature may be
responsible for observations of a tight coupling
between the population dynamics of root cyst
nematodes and those of their fungal endoparasite,
Hirsutella rhossiliensis (Jaffee, 1992).
This species can be grown in pure culture, and
although conidia generated in this way are
not infectious, hyphal inoculum might be
useful for biological control in the future
(Kerry & Jaffee, 1997).
Opportunistic egg and cyst parasites, notably
Pochonia chlamydosporia and Paecilomyces lilacinus,
possess a high ability to colonize plant roots in
agricultural soils, and are therefore potentially
useful in the biological control of plant-parasitic
nematodes. Both have suppressed root knot
and cyst nematodes in experiments under controlled
conditions (Siddiqui & Mahmood, 1996),
although a major problem is that egg masses or
cysts embedded in root tissue cannot be attacked
by either fungus (Kerry, 2000). Pochonia chlamydosporia
has been associated with the suppressive
properties of agricultural soils against the cereal
cyst nematode (Kerry et al., 1982).
25.2 Aquatic hyphomycetes
(Ingoldian fungi)
If a sample of foam from a rapid stream flowing
through deciduous woodland is examined
microscopically, especially in autumn after leaf
fall, it will be found to contain a rich variety
of conidia of unusual shape (Fig. 25.9). Many
are quite large, spanning 100 mm or more. These
conidia belong to aquatic hyphomycetes which
grow on decaying leaves and twigs. They are
also referred to as Ingoldian fungi in honour
of C. T. Ingold who pioneered their study. If
decaying leaves are collected from the stream
and incubated in a shallow layer of water at
a temperature of 10 20°C, numerous conidiophores
of these fungi will develop in a few
hours. Ingoldian fungi have a worldwide
Fig 25.9 Conidia of aquatic
hyphomycetes from river foam.
(a) Volucrispora sp. (b) Alatospora acuminata.
(c) Clavatosporalongibrachiata.(d)Tricladium
splendens.(e)Lemonniera aquatica.
(f) Lemonniera terrestris.(g)Articulospora
tetracladia.(h)Clavatospora stellata.
(i) Anguillospora crassa.(j)Anguillospora sp.
(k) Heliscus lugdunensis. (l) Unidentified.
(m) Margaritispora aquatica.
(n) Tumularia aquatica.